1. Field of the Invention
The present invention relates to a positioning module, an optical touch system and a method of a calculating coordinate of the touch medium, and more particularly, to a positioning module, an optical touch system and a method of calculating a coordinate of the touch medium that are able to actuate coordinate calculation when the touch medium contacts a touch panel.
2. Description of the Prior Art
A light source of the conventional optical touch module is disposed above the optical detector, the optical shelter path can be effective when an object is put into a projecting range of the light source, and the optical touch module can calculate the correct position of the object. However, position of the light source is higher than position of the camera of the optical detector. Beam emitted from the light source is shadowed by the object before the object contacts the touch plane, and the optical detector is actuated to detect motion of the object when the object does not contact the touch plane. As the light source and the optical detector are disposed on the same perpendicular plane, a dark area, which is formed when the beam emitted from the light source is shadowed by the object, is deviated because the optical detector misaligns with an optical path from the light source to the object, so that the optical detector can not calculate the correct position of the object according to the captured image. Thus, design of an optical touch system capable of actuating the coordinate calculation when the object contacts or almost contacts the touch plane for correct position of the object is an important issue in the optical touch industry.